Of course, within the framework of general relativity, the primitivists and the dispositionalists can simply restrict the scope of their account to globally hyperbolic spacetimes, which do not contain closed timelike curves and where the initial value formulation is well-defined; for instance, within Maudlin's primitivism, closed timelike curves are considered to be (meta)physically impossible. Despite the fact that it can be justified (to some extent) by cosmological considerations about our actual universe being globally hyperbolic (at least in a certain approximation), such a strong metaphysical attitude is not very satisfying from a naturalistic point of view, since it amounts to constraining a physical theory with metaphysical prejudices (about the need for some fixed spatiotemporal structure) while refusing to inform the metaphysical framework with physical insights (about the dynamical nature of spacetime).To be fair, [1]} does consider the possible need of revising his conception of laws in the light of new physics (“[f]uture theories may challenge the notion of time itself”). In any case, this attitude is not tenable in the context of quantum gravity where spacetime is not fundamental.
